<script
  crossorigin="anonymous"
  src="https://lib.baomitu.com/vue/3.1.4/vue.global.js"
></script>
<div id="counter">
  Counter: {{ counter }}
  <button @click="counter++">inc</button>
</div>
<script>
  const { createApp, ref } = Vue;
  const Counter = {
    setup() {
      const counter = ref(0);
      return { counter };
    },
  };
  createApp(Counter).mount("#counter");
</script>
